The phosphor is utilized in a fluorescent display tube (VFD: vacuum-fluorescent display), a field emission display (FED: Field Emission Display), a SED (Surface-Conduction Electron-Emitter Display), a plasma display panel (PDP: Plasma Display Panel), a cathode-ray tube (CRT: Cathode-Ray Tube), a liquid-crystal display backlight (Liquid-Crystal Display Backlight), a white light-emitting diode (LED: Light-Emitting Diode), and soon. In any of these applications, it is necessary to provide the phosphor with energy to excite the phosphor in order to make the phosphor emit fluorescence and the phosphor is excited by an excitation source with high energy such as a vacuum ultraviolet ray, an ultraviolet ray, an electron beam, and blue light so as to emit a visible light ray such as blue light, green light, yellow light, orange light, and red light.
As an example of such a phosphor, an oxynitride phosphor including a JEM phase as a main component represented by the general formula of (MAl(Si6-zAlz) N10-zOz) (here, M is one or two or more kinds of elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.) is known (for example, refer to Patent reference 1). According to Patent reference 1, it is disclosed that the oxynitride phosphor including La and Ce as the M element is a phosphor to emit blue light and that the oxynitride phosphor including La and Eu as the M element or the oxynitride phosphor including La and Tb as the M element is a phosphor to emit green light.
Further, an oxynitride phosphor including, as a main component, a JEM phase including an alkaline-earth metal has been developed (for example, refer to Patent reference 2). According to Patent reference 2, it is disclosed that the phosphor is an oxynitride phosphor activated by Ce and including a JEM phase as a main component, in which La is partially replaced with Ca, Sr, or Ba, so as to emit blue to green light having a wavelength of not exceeding 510 nm.
However, the phosphor including the JEM phase as the main component (hereinafter, also referred to as “JEM phosphor”), which has been developed as shown in Patent reference 1 or 2, is a phosphor to emit blue or green light. The emission intensity of the phosphor emitting the green light was low.